What to Do If You're Bitten by a Spider

For any arachnophobe, suffering a spider bite is the ultimate fear and a call to action for an exterminator, but the average spider doesn’t really mean you harm. The only reason most spiders will go out of their way to bite a person is because they feel threatened. They’ll give you a defensive bite if you disturb their hiding place or roll over them in bed in the middle of the night, but it’s unlikely that a spider will bite you for no reason. However, if you have been bitten by a spider, what exactly should you do?

Diagnosing the Bite

Many people wake up in the morning to find a mysterious rash or bump and immediately think a spider is to blame, but spider bites are actually quite rare. Unless you saw the spider in action it’s more likely the work of some other insect (most spider bites are pretty indistinguishable from various bug bites), and if a spider truly does bite you, you probably won’t be able to tell until hours later. The first step to accurately treating a spider bite is knowing that it actually is a spider bite, so you’ll need to diagnose it beforehand.

The Symptoms

Itching or swelling

Rashes or hives

Muscle pain/spasms or cramping

Pain around the area of the bite

Stiffness or aching joints

Difficulty breathing and/or coughing

Fever, sweating, and/or chills

Headache

Nausea and vomiting

Spiked blood pressure

Numbness or tingling around the bite

Allergic reaction

The Physical Appearance

There is no universal way to identify a spider bite solely by sight alone. Different spider types will elicit different types of bumps, rashes, or sores, and one spider alone can cause a range of reactions in different people. So, while relying on physical appearance alone is unreliable to diagnose a spider bite without doubt, in conjunction with the aforementioned symptoms you can get a better idea of whether you’ve been bitten by a spider or some other insect.

How Do You Know If They're Venomous?

Calling a spider “venomous” brings to mind a frightening and uncommon image, but the truth is that the majority of spiders use venom and fangs to kill their prey. Therefore, virtually all spiders can be classified as venomous. The catch is that, luckily for us, most spider poison can’t harm humans because it’s too weak, used to paralyze small insects long enough for the spider to make a meal of it and inadequately made for killing a person.

However, there are a handful of spiders that do produce venom strong enough to be harmful to humans. Most live outside of the U.S., but it’s a good idea to be familiar with two of these species that are the easiest to come across.

Black Widow: Black widows are fairly easy to identify thanks to the red hourglass marking on their black, shiny abdomen. They’re typically more common in the northern and southern parts of the United States, and make their home in dark, dry spots such as woodpiles, basements, garages, hollow stumps, and trash cans. They are considered to be the most venomous spider in the United States. Fortunately, they only bite humans when disturbed, and they don’t always inject their venom. The number of deaths attributed to black widows in the last ten years in the United States is practically nonexistent, but their bites will still cause a serious amount of pain and some unpleasant side-effects. They tend to be immediately painful, and will quickly develop swelling and red marks. Within the hour, the pain will intensify and spread throughout the body, perhaps reaching your back, chest, stomach, and head. Serious cases may include nausea, vomiting, difficulty breathing, and an increased heart rate.

Brown Recluse: Brown recluse spiders are non aggressive and rarely seen (as implied by their name, they tend to make their home in dark, secluded spots and like to steer clear of human interaction) but you can identify one by the dark brown violin-shaped mark on their backs, or by their six eyes–two in the front and two on each side of their body–instead of the traditional spider set of eight eyes in two rows of four. You may not notice you’ve been bitten at first, feeling a small sting if you feel anything at all, but over the following hours the pain and condition of the bite will worsen. It may blister, turning blue or purple with a red ring around it resembling a bullseye, and could develop into an open sore. Serious illness and death attributed to a brown recluse bite are rare, but the venom can cause necrosis (damage and death to the skin tissue), and in severe situations the harm can spread to deeper tissues. While there is no antidote, medical care centers around treating the wound and preventing any infection.

How to Treat Them

In most cases, you can treat nonvenomous spider bites at home without the need for professional medical assistance. Gently clean the bite and surrounding skin with soap and water. Once you’ve finished, apply some antibiotic cream and keep an ice pack on the area for 10 minutes intervals to reduce swelling. You can also take acetaminophen or ibuprofen for pain and an antihistamine to alleviate any swelling.

You should seek medical attention if:

Pain continues to worsen after 24 hours

Symptoms intensify instead of mitigating over time

The bite begins to discharge fluid

Open sores, blisters, or discolorations develop

Redness spreads away from the bite

The bite and surrounding skin begin to numb or tingle

An allergic reaction induces anaphylactic shock

Loss of consciousness occurs

Tissue surrounding the bite begins to die

If you know the bite has come from a venomous spider (whether because you saw the spider or know you are experiencing the symptoms attributed to a venomous bite), there are immediate steps you can take even before getting to the hospital. Try to tie a snug bandage above the bite, and if it’s on a limb, elevate it to help slow or stop the venom spreading to the rest of the body. If you can safely do so, try to bring the spider in question with you, even if it’s dead. Your doctor can use it to determine the best course of treatment based on the species.